Steam boiler heated by waste heat

ABSTRACT

Process gas of high temperature and under high pressure from naphtha reformers or the like is used in a heat-exchanging steam boiler for generating steam for the use in the reforming process itself and for other purposes such as in steam turbines whereby the hot gas is cooled at the same time.

United States Patent [72] Inventors ShomNarita;

Masaki Ojima; Asahiko Shiraishi, Kobe Japan Feb. 12, 1969 May 1 l, 1971 Kawasaki J ukogyo Kabushiki Kaisha Kobe Japan Feb. 14, 1968- Japan Appl. No. Filed Patented Assignee Priority STEAM BOILER HEATED BY WASTE HEAT 6 Claims, 6 Drawing Figs.

US. Cl 122/7 Int. Cl F22b 1/18 [50] FieldofSearch 122/7, 338

[56] References Cited UNITED STATES PATENTS 2,195,274 3/1940 Ferguson 122/7 2,840,050 6/1958 Sprague et al. 122/338 3,254,634 6/ 1966 Vorkauf 122/ 7X Primary Examiner-Kenneth W. Sprague Attorney-Sparrow & Sparrow ABSTRACT: Process gas of high temperature and under high pressure from naphtha reformers or the like is used in a heatexchanging steam boiler for generating steam for the use in the reforming process itself and for other purposes such as in steam turbines whereby the hot gas is cooled at the same time.

PATENTED mm 1 Ian SHEET 1 BF 3 ATTORNEYS PATENTED HAY] 1 IE1?! sum ear 3 PATENTED MAN 1 as? I v sum 3 BF 3 ATTORNEY5 STEAM BOILER HEATED BY WASTE HEAT BACKGROUND OF THE INVENTION The invention relates to steam-generating boilers of the heat exchanger type for using waste heat of chemical processes, in particular to a heat exchanger for using the high-temperature, high-pressure process gas from naphtha reformers or the like, cooling this waste gas at the same time.

Steam boilers of the heat exchanger type for using waste heat of process gases of industrial processes are known. In these known apparatus the gases do not have very high temperatures and particularly not very high pressures. The steam generated by these devices did not have to respond to demands for high pressure either and the process gases after having exchanged their heat are of no further use. Heat exchange boilers for these purposes have conventionally horizontally or only slightly inclined smoke tubes surrounded by the water to be heated. There are also no greater heat stresses in the structures of such heat exchangers than can be found in any conventional steam boilerjHowever, chemical processes such as stream reforming of hydrocarbons are performed under conditions of very high temperature and of high pressure. The hot process gases have to be cooled after leaving the reformer for further processing. Heat exchanger for using the waste heat of such process gases cannot be built like conventional structures of this king. By this invention the problems involved by these conditions are solved.

SUMMARY The invention consists in such novel features, construction arrangements, combinations of parts and improvements as may be shown and described in connection with the apparatus herein disclosed by way of example only and as illustrative of a preferred embodiment. The inventive idea of this new structure is to make proper use of the waste heat of the high temperature and of the high pressure of the process gas and to generate steam of high pressure which in turn can be used for the reforming process itself, and obviously for other uses as well, such as generating power in steam turbines.

Objects and advantages of the invention will be set forth in part hereafter and in part will be obvious herefrom or may be learned by practicing the invention. The same being realized and attained by means of the instrumentalities and combinations pointed out in the appended claims.

It is an object of the invention to provide a steam boiler for using the waste heat of high-temperature, high-pressure process gas.

It is another object of the invention to provide a structure of a heat-exchanging device operating under heavy conditions of heat and pressure, with relatively less heavy material.

Furthermore, it is an object of the invention to provide steam and water tube structures protecting the tube material from undue stresses caused by high thermal loads.

Yet another object of the invention is to provide a proper heat protection of the external structure of the heat exchanger.

A further object of the invention is to provide an inside wall of the heat exchanger consisting of the tubes as the bypass duct of the process gas of the steam boiler heat exchanger.

Various further and more specific purposes, features and advantages will clearly appear from the detailed description given below taken in connection with the accompanying drawing which forms part of this specification and illustrates merely by way of example one embodiment of the device of the invention.

BRIEF DESCRIPTION OF THE DRAWING In the following description and in the claims, parts will be identified by specific names for convenience, but such names are intended to be as generic in their application to similar parts as the art will permit. Like reference characters denote like parts in the several figures of the drawing, in which:

FIG. 1 shows schematically the axial section of the waste heat exchange boiler;

FIG. 2 shows a cross section of the boiler shown in FIG. 1, taken along the line 2-2 of FIG. 1;

FIG. 3 is a schematical view of the axial section of another embodiment of the waste heat exchangeboiler;

FIG. 4 shows an axial section of the upper part of the waste heat exchange boiler in an enlarged scale, conforming to the schematic section shown in FIG. 1;

FIG. 5 shows an axial section of the lower part of the waste heat exchange boiler in the same enlarged scale in FIG. 4, conforming to the schematic section shown in FIG. 1;

FIG. 6 shows a cross section of the upper part of the boiler shown in FIG. 4, taken along the line 6-6 in FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now in more detail to the drawing illustrating a preferred embodiment by which the invention may be realized, there is schematically shown in FIG. 1 the axial section of the waste heat exchange boiler of this invention. The boiler consists of a vertically oriented elongated body with a relatively thin outer shell which is lined inside with a layer of refractory material 12. Above the boiler but separated therefrom is a steam drum 13. Water tubes 14 lead the .water downward into the boiler, where the lower common header 15 is located, which consists of a suitable number of ring-shaped tubes 16. Water tubes 17 form an outer wall inside the boiler, wherein the water rises by convection upwardly to the upper common header 18 which consists also of a suitable number of ringshaped waterand steam-collecting tubes 19. Steam-generating tubes 20 are connected to ring-shaped tubes 16 of lower header l5 and are distributed inside the boiler, filling as much as possible the inner space of the boiler. Tubes 20 lead upwardly to upper header 18 where the ring-shaped tubes 19 are connected to the return tubes 21. Water tubes 14 are located inside upper common header 18 up to the point where the two tubes are separated after they had emerged from the upper part of the boiler. Water and steam are collected in upper header I8 and ring tubes 19 and returned through return tubes 21 in steam drum 13, whereas the water falls downward through tubes 14, which are located inside the upper headers 18 to lower headers 15.

The hot process gases having a temperature of approximately 1,000 C. and a pressure of approximately 30 atm. enter the boiler through the opening 22 at the lower end thereof, flowing through the bundle of tubes 20 and leave the boiler through the upper outlet 23 after having given offa substantial amount of their'heat for converting the water into steam. The center opening between the innermost steam tubes 20 is closed by a damper 24 for controlling the flow of the process gas.

The arrangement of downflow water tubes 14 inside upper common header 18 has the advantage of protecting outer shell 11 and upper common headers 18 from undue heat stresses at the point where the headers penetrate outer shell 11. Furthermore,'the arrangement of water tubes 17 whichlead the water from drum 13 downwardly to form actually the wall of the boiler so that the outer shell 11 does not'have to be as thick as if it would have to be without the protection afforded by these tubes. The overall structure of the waste heatexchange boiler provides also for a satisfactory boiler water circulation even under a high heat load, due to the simplicity of the tube circuit arrangement.

FIG. 3 shows a modification of the boiler shown in FIG. 1. In this modification downflow water tubes 14 are not located inside upper common header 18 but penetrate outer shell 11 as close to one another as possible in order to avoid thermal stresses caused by water tubes 17, steam tubes 20 and downflow tubes 14.

While the invention has been described and illustrated with respect to a certain preferred example and a modification of the boiler which gives satisfactory results, it will be understood by those skilled in'the art after understanding the principle of the invention, that various other changes and modifications may be made without departing from the spirit and scope of the invention.

We claim:

1. A waste heat exchange boiler for generating steam using gases of high temperature and of high pressure of chemical processes while cooling said gases, said boiler having a substantially vertically oriented elongated body having an opening at the lower end and an opening at the upper end thereof, said body having an outer shell and a heat-insulating lining in said shell, said lining consisting of refractory material, and having a steam drum separately arranged from said body; said boiler comprising upper and lower common headers, both said headers consisting of a plurality of substantially ring-shaped steam tubes, said rings disposed in parallel relationship to one another, a plurality of first water tubes leading downwards from said drum to said lower headers, connecting tube means between said lower headers and said upper headers and a plurality of return tubes leading upwards from said upper headers to said-steam drum, said first water tubes being located concentrically inside said upper headers up to a point where said return tubes had penetrated said outer shell.

2. A waste heat exchange boiler according to claim I, and a plurality of second water tubes arranged in said refractory lining in a side-by-side relationship, said second water tubes connecting said upper with said lower common headers, said second water tubes protecting said refractory lining from said high-temperature, high-pressure gases.

3. A waste heat exchange boiler according to claim 2, said connecting tube means comprising a plurality of steamgenerating tubes forming a bundle filling most of the inner space of said body, said steam-generating tubes connecting said upper with said lower headers while permitting said heati said shell, said lining consisting of refractory material, and

having a steam drum separately arranged from said body; said boiler comprising upper and lower common headers, a plurality of first water tubes leading downwards from said drum to said lower headers, connecting tube means between said lower and said upper headers and a plurality of steam tubes leading upwards from said upper headers to said steam drum, said first water tubes and said steam tubes disposed for penetrating said shell separately but in close proximity of one another.

5. A waste heat exchange boiler according to claim 4, and a plurality of second water tubes arranged in said refractory lining in a side-by-side relationship, said water tubes connecting said upper with said lower common headers, said water tubes protecting said refractory lining from said high-temperature, high-pressure gases.

6. A waste heat exchange boiler according to claim 4, said connecting tube means comprising a plurality of steamgenerating tubes forming a bundle filling most of the inner space of said body, said steam-generating tubes connecting said upper with said lower headers while permitting said heatexchanging gases to flow through said bundle. 

1. A waste heat exchange boiler for generating steam using gases of high temperature and of high pressure of chemical processes while cooling said gases, said boiler having a substantially vertically oriented elongated body having an opening at the lower end and an opening at the upper end thereof, said body having an outer shell and a heat-insulating lining in said shell, said lining consisting of refractory material, and having a steam drum separately arranged from said body; said boiler comprising upper and lower common headers, both said headers consisting of a plurality of substantially ring-shaped steam tubes, said rings disposed in parallel relationship to one another, a plurality of first water tubes leading downwards from said drum to said lower headers, connecting tube means between said lower headers and said upper headers and a plurality of return tubes leading upwards from said upper headers to said steam drum, said first water tubes being located concentrically inside said upper headers up to a point where said return tubes had penetrated said outer shell.
 2. A waste heat exchange boiler according to claim 1, and a plurality of second water tubes arranged in said refractory lining in a side-by-side relationship, said second water tubes connecting said upper with said lower common headers, said second water tubes protecting said refractory lining from said high-temperature, high-pressure gases.
 3. A waste heat exchange boiler according to claim 2, said connecting tube means comprising a plurality of steam-generating tubes forming a bundle filling most of the inner space of said body, said steam-generating tubes connecting said upper with said lower headers while permitting said heat-exchanging gases to flow through said bundle.
 4. A waste heat exchange boiler for generating steam using gases of high temperature and of high pressure of chemical processes while cooling said gases, said boiler having a substantially vertically oriented elongated body having an opening at the lower end and an opening at the upper end thereof, said body having an outer shell and an heat-insulating lining in said shell, said lining consisting of refractory material, and having a steam drum separately arranged from said body; said boiler comprising upper and lower common headers, a plurality of first water tubes leading downwards from said drum to said lower headers, connecting tube means between said lower and said upper headers and a plurality of steam tubes leading upwards from said upper headers to said steam drum, said first water tubes and said steam tubes disposed for penetrating said shell separately but in close proximity of one another.
 5. A waste heat exchange boiler according to claim 4, and a plurality of second water tubes arranged in said refractory lining in a side-by-side relationship, said water tubes connecting said upper with said lower common headers, said water tubes protecting said refractory lining from said high-temperature, high-pressure gases.
 6. A waste heat exchange boiler according to claim 4, said connecting tuBe means comprising a plurality of steam-generating tubes forming a bundle filling most of the inner space of said body, said steam-generating tubes connecting said upper with said lower headers while permitting said heat-exchanging gases to flow through said bundle. 